1. Field of the Invention
The present invention relates to surgical orthopedic cutting instruments, and more particularly relates to an improved cutting block apparatus for shaping the distal femur of a patient prior to the placement of a knee joint prosthesis. Even more particularly, the present invention relates to a distal femoral cutting block apparatus that allows a surgeon to select a knee prosthesis using an anterior or a posterior referencing technique when the anterior/posterior dimension falls in between available inventory sizes (typically one or more millimeters apart in size).
2. General Background
In knee joint replacement surgery, the surgeon often replaces the distal femoral surface of the patient's knee with a curved metallic prosthesis. The prosthesis has a generally smooth continuous outer curvature that faces a corresponding component that is attached to the patient's tibia. The posterior surface of the femoral component is typically provided with a number of intersecting flat surfaces. A common femoral component of a knee prosthesis provides five intersecting flat surfaces. One of the surfaces is adapted to engage the anterior cortical surface of the femur. Another of the flat surfaces is adapted to face the posterior surface of the femur. Yet another surface is adapted to engage the distal end of the patient's femur. Additionally, a pair of chamfer surfaces form diagonally extending surfaces which form an interface between the distal surface and the respective anterior and posterior surfaces.
A surgeon forms five (5) separate cuts on the patient's distal femur in order to prepare the distal femur to receive the femoral prosthesis. One of the problems facing the surgeon is the proper orientation of the cuts so that the prosthesis will fit the femur with the correct orientation. One method of orienting a cutting guide is to reference that cutting guide to a rod that is placed in the patient's intramedullary canal.
A number of patents have issued which disclose medical cutting instruments for use by orthopedic surgeons. Some of these cutting instruments relate to shaping of the distal femur or adjacent bone structure.
U.S. Pat. No. 4,474,177 is an example of a cutting block instrument that references a cutting guide to an intramedullary rod that is positioned in the patient's intramedullary canal of the femur.
The Whiteside U.S. Pat. No. 4,467,801, entitled "Method And Apparatus For Shaping A Proximal Tibial Surface", provides a method and apparatus for preparing the proximal surface of a tibia to receive a proximal tibial prosthesis employing a reamer/alignment guide which is used to internally locate the central long axis of the tibia and a plateau planar which cooperatively engages with a guide handle attached to the reamer/alignment guide to accomplish the shaping of the proximal tibial surface. The reamer/alignment guide has a rod portion extending into the interior of the tibial shaft whose central long axis corresponds with the central long axis of the tibia. The guide handle is concentric with that rod portion such that the plateau planar assumes the proper alignment with respect to the central long axis of the tibia such that the proximal tibial surface is shaped relative to that axis in a simple and accurate manner.
European Patent Application No. 0 122 669 discloses a guide for femoral neck osteotomy that comprises a longitudinal rod having attaching structure at the lower end thereof for securing the rod to a femur at the greater trochanter. A transversely extending support arm is secured to the rod adjacent the lower end thereof, and a guide bar is connected to the support arm. The guide bar has at least one elongate planar surface disposed at an angle of 45.degree. to the axis of the rod. In use, the rod is aligned with the long shaft axis of the femur and attached to the femur at the greater trochanter. The rod is manipulated until the support arm and the long shaft axis of the tibia are disposed in the same plane. This procedure properly positions the elongate planar surface of the guide bar whereby an instrument in engagement with that surface traverses the femoral neck at an angle of 45.degree. to the long shaft axis of the femur.
Another Whiteside U.S. Pat. No. 4,474,177 provides a method and apparatus for preparing the distal surface of a femur to receive a distal femoral prosthesis employing an intramedullary reamer which is used to internally locate the central long axis of the femur, an intramedullary alignment guide which is inserted into the space left in the intramedullary canal upon removal of the reamer and at least one femoral surface modifying instrument which cooperatively engages with a guide handle attached to the intramedullary alignment guide to accomplish the shaping of the distal femoral surface. The intramedullary alignment guide has a rod portion extending into the femoral intramedullary canal whose central long axis corresponds with the central long axis of the femur. The guide handle is attached to that rod portion at a preselected angle such that the shaping instruments fixed thereto assume the proper alignment with respect to the central long axis of the femur such that the distal femoral surface is shaped relative to that axis in a simple and accurate manner.
An improved triplanar knee resection system, disclosed in U.S. Pat. No. 4,487,203, provides a system for preparing a knee joint for a prosthesis. The apparatus of the triplanar knee system includes a single guide member for use in resecting the distal femoral condyles, the proximal tibia, and the distal femur. The guide member cooperates with a simplified set of instruments, including femur and tibia guide rods, a tibia adaptor, a tibia bar, and a femur bar, for establishing equal flexion and extension gaps and triplanar resections. The method of the triplanar knee system provides a simplified procedure for use by an orthopedic surgeon in properly preparing a knee joint for implantation of a prosthesis.
U.S. Pat. No. 4,567,885 also provides an improved triplanar knee resection system for preparing a knee joint for a prosthesis. The apparatus of the triplanar knee system includes a single guide member for use in resecting the distal femoral condyles, the proximal tibia, and the distal femur. The guide member cooperates with a simplified set of instruments, including femur and tibia guide rods, a tibia adaptor, a tibia bar, and a femur bar, for establishing equal flexion and extension gaps and triplanar resections. The method of the triplanar knee system provides a simplified procedure for use by ann orthopedic surgeon in properly preparing a knee joint for implantation of a prosthesis.
The Petersen U.S. Pat. No. 4,567,886 discloses a spacer guide for utilization in total knee surgery for establishing size of prosthesis and position of cuts for total knee replacement surgery includes a generally L-shaped base member for attachment to the anterior femoral cortex of a prepared femur with a generally L-shaped adjustable support member adjustably secured to the base support member and a vertically positionable indicator slide having a squaring jig for cooperative engagement and alignment with the cutting head of a tibia alignment and resection guide for squaring the tibia and femur and including indicator means for indicating the position of a tibia plateau cut and indicating the size and positioning for a distal femoral cut for indicating the sizing of the both the tibial and femoral prostheses.
The Kenna et al. U.S. Pat. No. 4,464,729 discloses a prosthetic knee implanted after cutting the femur and tibia with the aid of instruments which include axial alignment guides and a series of cutting jigs.
A method and apparatus for resecting a distal femoral surface is disclosed in U.S. Pat. No. 4,703,751 in which an intramedullary rod is inserted through the distal surface of the femur and along the femoral shaft access, leaving a protruding end; a jig is attached to the protruding end, the gig having a shaft for receiving the rod end and a support plate attached to an end of the shaft and extending parallel to the rod; attaching a reference bar to the shaft, the bar having a pair of opposing flanges and a central opening which receives the shaft therethrough, and adjusting the bar on the shaft such that the flanges contact condylar apices of the femur; fixing the jig relative to the femur; attaching a cutting plate to the jig, the cutting plate having blade guides thereon, pivoting the cutting plate relative to the jig such that the blade guides made a predetermined angle with the rod, and securing the cutting plate to the jig; and inserting a saw blade through the blade guides to make a resection of the distal femoral surface. In the preferred embodiment, the shaft includes a plurality of bores along its length, each sized to receive the rod therethrough so that the distance between the rod and the support plate may be adjusted to accept different sized anterior femur portions. Also in the preferred embodiment, the apparatus includes a plurality of guide bars, each sized to space the blade guides a predetermined distance from the condylar apices.
The Kaufman et al. U.S. Pat. No. 4,721,104 relates to a surgical apparatus for providing an accurately recess in a distal femoral surface for the intercondylar stabilizing housing of a posterior-stabilized knee implant prosthesis which apparatus comprises a template having a bottom surface which is adapted to be placed in an aligning relationship with the flat surface of a distal femur which has been partially shaped to receive the femoral component of a posterior-stabilized knee implant prosthesis and a U-shaped slot passing through the template where the slot is of substantially the same size and shape as the outer periphery of the intercondylar stabilizing housing present on the femoral component to be implanted and a drilling means, preferably in the form of an endmill cutter, having a stop means thereon and the drilling means closely engages the sides of the U-shaped slot in the template so that the drilling means can be passed through the U-shaped slot until the stop means contacts a surface of the guide and is then drawn along the slot to create a precisely shaped and aligned recess in the femur for receipt of the intercondylar stabilizing housing. In a more preferred embodiment, the template is composed of a drilling means guide which fits over a femoral trial prosthesis which is used for trial reductions after the drill guide is used and removed.
The Russell et al. U.S. Pat. No. 4,722,330 relates to distal femoral surface shaping guide for mounting on a intramedullary alignment guide which references the central long axis of the femur in shaping the distal femoral surface and a method for shaping the distal femur using the shaping guide. The alignment guide of the present invention is adjustable relative to the surface of the anterior femoral cortex to insure that the anterior aspect of the distal femoral condyles is resected relative to that surface and, preferably, at the same level as that surface. The alignment guide of the present invention provides a main body which remains attached to the intramedullary alignment guide throughout the entire shaping of the distal femur. It thus requires fewer cutting guides and alignment steps than other shaping guides while allowing greater accuracy in shaping the distal femur relative to the central long axis of the femur.
An improved tibial cutting jig is disclosed in U.S. U.S. Pat. No. 4,736,737, provided for use in obtaining accurate tibial resection in the course of a total knee prosthesis implantation procedure. The tibial cutting jig includes a base for sliding reception onto an intramedullary alignment rod preinstalled generally along the longitudinal axis of the tibia. The base includes laterally extending outriggers carrying removable measurement keys of selected size for spacing the base above the tibial plateau by a selected dimension. An anterior saw guide depends from the base and is thus positioned relative to the tibial plateau in accordance with the sizes of the measurement keys.
The Buechel et al. U.S. Pat. No. 4,738,253 discloses a guide for a cutting device used to make a surgical cut in a first bone in desired spatial relationship with a pre-existing cut in a second bone is disclosed to include a means for contacting the pre-existing cut to establish a reference for the desired spatial relationship and a body member engaging the means for contacting and including a guide surface for establishing the desired spatial relationship and guiding a surgical cutting tool to cut the first bone in a plane which is not normally inclined with respect to the long axis of the first bone.
Another Buechel et al. U.S. Pat. No. 4,738,254 discloses a positioner for positioning a surgical instrument which acts as a guide for a cutting instrument which produces a surgical cut in an anatomical structure; in one embodiment the positioner positions a surgical instrument which acts as a guide for the cutting instrument at a predetermined position with respect to a previously resected surface whereby a further resection is made at a predetermined position with respect to the previously resected surface; and in a further embodiment the positioner acts as a adaptor for a surgical instrument which aids in producing surgical sections thereby allowing the surgical instrument to produce surgical cuts at various predetermined positions relative to a previous surgical cut made at one of several levels.
The Dunn et al. U.S. Pat. No. 4,759,350 provides a system of instruments for shaping the distal femur and proximal tibia surfaces to receive components of a knee prosthesis for knee replacement surgery. The system references the femur intramedullary channel with a femoral alignment guide to prepare the distal femur that, in turn, is a reference for several cutting guides for sequential attachment to the femoral alignment guide and prepared bone surfaces whereby the prepared distal femur is prepared to a flat surface that is perpendicular to the patient's mechanical axis with bone surfaces adjacent thereto sectioned to surfaces that are at right angles to that distal femur surface with chamfers therebetween to receive the femur component of a knee prosthesis. A tibial cutting guide is provided for preparing the proximal tibia that consists of a sleeve, with a tube telescoped therein, the ends thereof including pin arrangements for connecting them into the tibia, between the ankle and near the proximal tibia, an open tube end of the tibial cutting guide to receive a rod telescoped therein that mounts a cutting guide platform and includes a screw arrangement for releasably maintaining the road and tube together. The cutting guide platform includes a body with a saw guide slot formed therethrough to receive a saw blade to cut across the proximal tibia to form a surface for accommodating a tibial component of the knee prosthesis, the cutting guide platform body further including an arrangement for securing it to the tibia, slightly below the proximal tibia, and a tibial resection guide for setting a depth of cut across the proximal tibia.
U.S. Pat. No. 4,773,407 issued to Petersen discloses a method and instruments for resection of the distal femur. The instruments include a distal femoral resector and a femoral alignment guide/rod. The distal femoral resector is designed to be attached to the distal femur on a plane filed on the anterior femoral cortex. The distal femoral resector includes a feeler gauge laterally adjustable to adapt to the intercondylar notch of the particular patient and further includes a rotating rod having openings therethrough for fastening pins, which rotating rod is designed to facilitate the placement of the resector on the anterior femoral cortex in a flush manner. The femoral alignment guide/rod includes a plate insertable within a slot in the resector designed for the insertion of the cutting tool and further includes a pivotable rod which may be utilized to align the resector with the mechanical axis of the leg. The rod may then be pivoted to a position facilitating the insertion of a fastening pin through the resector. The method of operation using these instruments is also disclosed.
U.S. Pat. No. 4,892,093 issued to Zarnowski et al. discloses a cutting guide for guiding a saw blade during the preparation of a femur for the implant of the femoral component of a knee prothesis includes guide surfaces for enabling the cutting of all four of the anterior femoral cut, the posterior femoral cut, the anterior chamfer and the posterior chamfer, fully and completely, with certitude and accuracy, while the cutting guide remains located and secured to the femur in a single position on a transverse surface located along the distal femur.
The Dale et al. U.S. Pat. No. 4,893,619 discloses a device for guiding an osteotomy to be performed on the proximal end of a humerus that has a proximal saw guide alignable on a selected surface of the proximal end of the humerus for defining a saw line thereon; a radial arm connecting the saw guide to a distal mechanism for stably aligning the saw guide, the distal alignment mechanism has a pair of opposing lateral and medial epicondyle arms pivotally engagable with the lateral and medial sides of the distal end of the humerus, the epicondyle arms being pivotally mounted in a distal cross arm, the distal end of the radial arm being slidably mounted in the cross arm for distal to proximal slidable movement therein; the proximal end of the radial arm being rotatably connected to the saw guide through a proximal guide bar; the radial arm being supported above the humerus by the proximal guide bar and the epicondyle arms.
U.S. Pat. No. 4,907,578 relates to an improved method and instruments for a resection of the distal femur. The parent application discloses a femoral alignment guide/rod including a plate insertable within a guide slot in the resector which is also used for the guided insertion of a cutting tool. The present invention improves upon this structure by providing an auxiliary attachment member on the resector allowing attachment of a new femoral alignment guide/rod on the resector housing proximal to the cutting tool guide slot, which new guide/rod allows easier access to various resector components. In a further aspect, structure is provided allowing the use of the resector with an intramedullary rod to increase accuracy. In this aspect, a gauge is incorporated in the resector which allows compensation for the angle between the mechanical axis of the leg and the longitudinal extent of the internal cavity of the femur while also allowing compensation or correction for specific anatomical conditions such as, for example, valgus correction.
The Whiteside et al. U.S. Pat. No. 4,935,023 relates to a distal femoral surface shaping guide for mounting on an intramedullary alignment which references the central long axis of the femur in shaping the distal femoral surface and a method for shaping the distal femur using that shaping guide with particular applicability for shaping one condyle for attachment of a unicondylar prosthesis. The alignment guide of the present invention is adjustable relative to the surface of the condyle to insure that the distal femoral condyle is resected relative to that surface. The alignment guide of the present invention utilized visual sighting studs and provides a main body which remains attached to the intramedullary alignment guide throughout the entire shaping of the distal femur.
The Bowman et al. U.S. Pat. No. 4,952,213 discloses an apparatus for placing a bone cutting saw cutting guide adjacent a proximal surface of a human tibia bone having an elongated rod inserted into the tibia for clampingly supporting a rotating bar on the central longitudinal axis of the tibia bone. The bar being extended from the rod and connected to a pivot device which in turn is connected to a support arm that holds a saw cutting guide against a proximal portion of the tibia bone. The rotation angle of the rod determining the medial-lateral inclination of the saw cutting guide and the pivot device determining the anterior-posterior inclination of the saw cutting guide. The support arm is adjustable in length to determine the height of the saw cutting guide.
The Dunn et al. U.S. Pat. No. 4,959,066 provides an osteotomy guide assembly for femoral neck osteotomy and includes a saddle locator assembly and a saw guide attachment. The saddle locator assembly includes a barrel-shaped locating device that locates the saddle region of the proximal femur. The barrel further includes a transverse support bar extending from the barrel. The barrel is positioned over an intramedullary shaft which is temporarily positioned in and extends from the medullary canal of the femur. A saw guide is used in conjunction with a saddle locator assembly. The saw guide is attached to the support bar by a single locking means which provides for positional adjustment of the saw guide relative tot he support bar in two directions, including adjustment in the anterior-posterior direction along the transverse support bar and axially along the femur via a post which extends from the saw guide.
The Whiteside et al. U.S. Pat. No. 5,002,545 provides a shaping guide to permit accurate shaping of the tibial plateau while saving the anterior cruciate ligament. An alignment rod is located anterior to the anterior cruciate ligament and along the anterior cortex of the intramedullary canal of the tibia provides points of reference for all shaping operations. The shaping guide of the present invention is adjustable with respect to the handle portion of the rod so that the amount of resection of the tibial plateau can be controlled readily by the surgeon by raising or lowering of the cutting guide surfaces for resection of the tibia.
The Mikhail et al. U.S. Pat. No. 5,108,405 discloses a system for performing hip prosthesis revision surgery includes a trial femoral component having a passageway which, upon insertion in the cavity left after removal of the original prosthesis, provides guide means for drilling a channel to receive a guide wire which, upon removal of the trail femoral component, serves as guide means for progressively larger reamers.